Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 5 · Portents, Comets
ग्रहचारः केतवश्च
कूक्रं वक्रमुखं ज्ञेयं सस्यवृष्टिविनाशकृत् ।कुजे त्रयोदशे ऋक्षे वक्रिते वा चतुर्दशे ॥ २९ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 29.
... that turning back is known as Vakramukha. It may harm crops and rain. If Mars turns back in the 13th or 14th nakshatra (star) ... (Our text is unclear here: a word before the name is garbled.)
Simple meaning: Mars turning back in the 10th to 12th star may harm crops and rain.
बालास्यचक्रं तत्तस्मिन्सस्यवृष्टिविनाशनम् ।
Mars turning back in the 13th or 14th star may harm crops and rain.
दुर्भिक्षं क्षुद्भयं रोगान्करोति क्षितिनंदनः ।
Mars turning back in the 15th or 16th star can bring famine, hunger and illness.
दुर्भिक्षं धनधान्यादिनाशने भयकृत्सदा ।
A Mushala turn tends to bring famine and fear of losing wealth and grain.